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Nike Air Zoom Structure 23 Multi-Tester Review

   The Nike Structure series has appeared to be in limbo the last few years. The previous several versions were very clunky and so bad I wasn't willing to spend my own money on a pair. Rumors began circling regarding the Structure 23 being something different and it is. Version 23 of Nike's classic stability trainer only similarity to previous versions is the name. Gone is a post/wedge, gone is the weirdly fitting upper, gone is the incredibly harsh ride, gone is even the stability classification (by Nike). Instead we have something different. A stable shoe with some enlightened concepts of stability, a better ride and fit than previous, but still with some work needed. 



Specifications (per Nike)
Weight: 10.2 oz (men's size 9)
Measured Weight: 10.9 oz (men's size 10)
Stack Height: 22 mm / 14mm
Drop: 8 mm
Classification: Stable Daily Trainer



HIGHLIGHTS

Matt: The Air Zoom Nike Structure 23 returns (from the dead?) as a brand new shoe. No longer listed as a stability shoe, the Structure 23 is a stable shoe for those wanting a slightly firmer ride for easy, uptempo and long runs. Featuring a continuation of a forefoot zoom unit, but the addition of several new age stability features and a data driven heel crash pad. Although a bit stiff, the overall transition has improved from previous versions and is another example of the evolution of our concept of a stability shoe. 

David: The Nike Air Zoom Structure 23 is an interesting shoe that rides between neutral and stability right in the grey area. The shoe provides a traditional daily trainer ride with some new age features like updated geometry as well integrating a crash pad design in the heel. The shoe itself isn't anything overly raving, but a consistent and pleasant shoe to run in for many miles. 




FIT

Matt: The Structure 23 fits true to size in my normal size 10. The fit is best described as "structured" and a little wide. There is a stiff heel counter in the rear. It has cushioning in the heel collar up higher, but the counter is right up against the heel in the lower half. Those with sensitive calcani (heel bones) should be wary of this shoe. The heel is average width, but with the stiff heel counter the lockdown is fairly good. The midfoot is a little wider than normal but feels secure.  There is an inner liner from the midfoot forward that provides an almost sock like fit. The laces do pull and secure the foot well on the platform and I have not had to lace lock the shoe. There is a surprising amount of room in the forefoot.  There is a distinct rounded toebox, but there is a semi structured toe guard that gives some structure to the front. The upper is a bit thick, which does provide plenty of structure. It is perforated, which does improve the breathability. 

David: The Structure 23 fits true to size, but does come with a really snug upper throughout. I am actually a half size up from my normal 9.5 and the shoe fits throughout like a normal trainer in my size would, but with accurate length for size 10. The shoe holds the foot well throughout with a thick and well constructed upper. The upper has a lot of padding built into it and it feels almost like a thick sock lining throughout. It has a tiny bit of give to it, but still very secure. The lockdown is good throughout and the toebox is spacious. Overall the upper provides a good lockdown and security while still having some breathability.




RIDE

Matt: The Structure 23 has a cushioned but stiff ride. I have heard other reviewers call the midsole soft, but that is not how it feels to me. There is no information on the midsole composition other than "CMP 010" on the medial heel. The midsole is thick enough that it provides plenty of protection particularly in the heel. However the ride is a bit firm up front due to the very stiff ride in the midfoot and forefoot. The heel has a great slightly lateral bevel that combined with a crash pad (data driven to optimize rate of sole compression) provides a smooth and slightly soft ride when landing at the rearfoot. The midfoot is stiff and stable, but transitions to a stiff forefoot. Despite the flex grooves, there is very little flex in the forefoot.  This combined with a late and minor toe spring creates a little extra work to get over the forefoot. The zoom air bag is mildly soft and bouncy when you land with a forefoot strike, but is less noticeable when you transition over it. There is an 8mm drop listed, which is lower than previous versions. This is not extremely noticeable thanks to the heel bevel.

David: The Structure 23 has a comfortable ride to it throughout with good transitions. The shoe well integrated heel bevel and crash pad to help with keeping movement linear. The outsole also mimics this by being more of a rim along the medial and lateral aspect of the rearfoot through the midfoot. The 8mmm drop feels accurate and is smoothened out well due to the geometry. The ride itself isn't anything overly amazing, but feels like a traditional daily trainer with some added stability. I'm thinking the traditional Nike Pegasus type ride, but with some updated geometry features like heel beveling and some sole flaring through the midfoot for added stability. The ride is right in between firm and soft and stays protective for many miles. The forefoot is on the stiffer end, but I did not have any problems with that, though you can feel the thickness of the outsole a tad throughout the forefoot when transitioning through toe off. 




STABILITY

Matt: Although the Structure 23 is no longer listed as a stability shoe (per Nike) and no longer appears to havee a post/wedge, there are several features that make this a very stable shoe. The last is a bit wider and there is some sole flare each direction. The midfoot is not narrow and instead sits on a broader platform. There are sidewalls in the heel and midfoot, which not only cradles the feet but may guide them. The ride is a bit firmer and as mentioned a bit stiff, which is inherently stable (again, it is slightly firmer for me, but based on other reviews may not be perceived that way by everyone). It should be again noted that there appears to be no post but there is the mild sensation of one. I can feel a little pressure under my arches. This may come from the geometric medial triangular wedge of midsole (see photo). Whether this is actually providing stability I have no idea, but I can feel the pressure at the top of the point. However, at most I would put this as a mild stability shoe. The true nature of the Structure 23 now is a structured/ mildly stable neutral shoe. Those with high stability needs will need to transition into this shoe, but those who want a stable shoe that are sensitive to posting will be right at home here. 

David: The Nike Structure 23 utilizes geometry and upper interaction to create stability. Like stated before the heel is beveled well and utilizes a crash pad through the heel and midline of the shoe through the midfoot. The shoe has sole flaring through the medial and lateral aspect of the shoe through that region as well. The forefoot also firms up and has full contact outsole from midfoot forward. The upper is built to last and not allow for translation while still being comfortable. The shoe is very stable for not having any "traditional" methods of stability built into it. 



SPEED

Matt: The Structure 23 is lighter and smoother than previous versions. That being said, it is still a daily trainer. The stiff ride feels OK at uptempo paces, especially if you land farther forward, but becomes too clunky at anything faster. The thick midsole is better for long runs, easy runs and recovery runs where you don't have to work too hard to transition over the stiff forefoot. 

David: The Structure 23 has some weight to it, but can respond a little bit if you ask it to since it has a firmer forefoot and smooth heel transition. For me though, this is primarily a daily trainer and easy day shoe. 
 




DURABILITY

Matt: The durability of the outsole on the Structure 23 is beyond anything I have seen this year. I have 60 miles on my pair and there is very little wear on the outsole. The upper continues to feel very structured (and a little stiff) with no signs of breaking down. The cushioning has softened a hair, but the ride has remained a bit stiff. Given that there has been little change, I expect the ride to remain consistent for a long period of time. Overall I expect a high number of miles out of these shoe, likely much more than the 300-500 mile industry standard.

David: Tank. The Structure 23 is built to last and hardly shows any wear after wear testing. I am using Matt's pair (who normally destroys shoes) and it still looks fine after my miles on it as well. The midsole is also still feeling the same as when I began running in it. Expect beyond industry standard here. 



THOUGHTS AS A DPT / FOOTWEAR SCIENCE

Matt: I have discussed the evolution of stability way too often, so please see our reviews of the Asics Gel Kayano Lite (Review) or our recent Youtube discussion on these trends (Youtube). What I would like to discuss is the design of the heel bevel.  As I have mentioned before, these are additions to a shoe that mimic certain designs/mechanisms in the body. There should be a heel bevel in a shoe, because it imitates the heel rocker. The heel rocker is the curve of the calcaneus, which helps maintain forward momentum by rolling the foot forward during initial contact (for heel strike). Toe spring imitates the forefoot rocker, which is the natural extension that occurs at the metatarsophalangeal joints (MTP joints). This extension also allows for a maintenance of forward moment and allows the foot to work as a lever. Too much or too little of each of these may cause problems, as different people need different amounts. The heel bevel is done very well. It has a smooth transition, which I would expect after analyzing data from tons of people to see how and where they land. The foam deformation is another component. The rate that foam deforms during contact will dramatically affect how soft or firm it feels. By optimizing this, you may be able to also influence the rate of loading that occurs. That rate may effect a large number of things. People activate their muscles at different rates. Some are fast and some are slow. That rate can be effect by things like plyometric training or the excitability of that person's nervous system. How fast that person can react to the impact forces from landing is simply a reaction, but may effect how much force is absorbed by active (muscles) or passive (joints, ligaments, etc) methods. That is why the heel bevel shape is not the only thing that effects landing. The rate of foam compression also will determine how long the person stays there or how fast they transition forward. There is not a perfect amount as certain people will have high vs low rate preferences (just like everything else).



RECOMMENDATIONS 

Matt: I think Nike is moving in the right direction with this shoe. The ride is improved, but something needs to be done regarding the transition at the front end of the shoe. The stiffness up front either needs to be rectified with deeper (and actually effective) flex grooves or by adding more toe spring to provide a smoother forefoot transition/toe off. The heel counter may also benefit from a little more cushioning on the inside to protect the calcaneus a bit more, but that is a personal preference. 

David: I like what Nike did here. Overall I am really happy with the Structure 23 but do think they can thin the upper a tad. It's cushioned and feels nice, but can come off as really thick. I think deepening the flex grooves in the forefoot might make the toe off a little bit more enjoyable in the later phases of the gait cycle at daily training paces. 


WHO THIS SHOE IS FOR (Conclusion)

Matt: The Nike Structure 23 is for those looking to regain hope in the structure series, but are ok with a shoe that has decreased its stability. This is a mild stability shoe at most and uses more methods of geometric stability rather than a post. The upper is wider, thick but secure. The midsole is cushioned, but has dichotomous personalities. A protective, smooth and slightly softer heel is paired with a stiff and firm forefoot. No longer listed as a stability shoe, the Structure 23 is a stable neutral/mild stability shoe meant for logging miles and recovery runs. The data driven heel is interesting and well done, but that forefoot needs a little more work to be the Structure we all remember and love. At least it is better than the last few versions. 

David: The Nike Structure 23 is a workhorse daily trainer for those who like a traditional daily trainer feel like the Nike Pegasus but would like a little more stability added into the shoe. The ride lies right in the middle between firm and soft and has a smooth softer heel landing with a slightly more stiff and firm forefoot toe off. The durability is incredibly high and the shoe will be able to take pretty much anything you throw at it. 


GRADING
Matt
Fit                   8  /10 (Plenty of room, but thick and stiff upper with mild irritation from stiff heel counter)
Ride                8  /10 (Smoother heel and protective, but too much stiffness in mid/forefoot)
Stability           9 /10 (Good structured shoe, but may not be enough stability for some)
Speed               8 /10 (Easy, long and uptempo runs. Overly stiff ride clunky at faster paces)
Durability       10 /10 (Extremely durable outsole, midsole and upper). 

David
Fit                   8.5  /10 (Thick upper throughout that can potentially be overly snug for some)
Ride                9  /10 (Nothing overly special, but really nice heel/midfoot, but firmer forefoot and consistent ride)
Stability           9.25 /10 (Really stable for a neutral shoe, but not enough to be a stability shoe, this falls right in the grey area)
Speed               8 /10 (Daily training and easy day efforts, a little too heavy and clunky at faster paces)
Durability       10 /10 (Extremely durable outsole, midsole and upper). 


Total Score: 87.75% (M: 8.6 /10, D: 8.95/10)

Thanks for reading!

TESTER PROFILES:
Dr. Matthew Klein is a 140 lb male with notable PRs of 14:45 for 5k and 2:32:44 for the full marathon.  He typically runs 70-100 miles per week and trains at a variety of paces from 8min per mile recovery runs to 4:40 per mile 1k repeats.  He prefers firmer and responsive shoes with snug heels and medium to wide toe boxes.  He is particular to less cushioned shoes and close to the ground shoes, but can handle a little cushion when he gets beat up.

Dr. David Salas is a 135 lb male with notable PRs ranging from 3:54 in the 1500m to 1:08:36 for half marathon. He typically runs 60 miles per week and trains from about 7:30 recovery runs to fast shorter efforts at 4:30 pace. He normally prefers neutral shoes with a firmer ride, but is completely open to other types of shoes.  He is a footwear enthusiast at heart and will always appreciate a high quality shoe when it comes around. For updates on training or testing, IG handle: @docsofrundavid


Editor's Note: As always, the views presented on this website belong to myself or the selected few who contribute to these posts. This website should not and does not serve as a replacement for seeking medical care. If you are currently injured or concerned about an injury, please see your local running physical therapist. If you are in the Los Angeles area, I am currently taking clients for running evaluations.

Matthew Klein, PT DPT OCS FAAOMPT
Doctor of Physical Therapy
Board Certified Orthopedic Clinical Specialist
Fellow of the American Academy of Orthopedic Manual Physical Therapists

Nathan Brown PT DPT MS
Doctor of Physical Therapy 
Masters in Anatomy and Clinical Health Science
Movement Performance Institute Certified in Advanced Functional Biomechanics 

David Salas PT DPT CSCS
Doctor of Physical Therapy
Certified Strength and Conditioning Specialist

***Disclaimer: These shoes were purchased for 20% off their retail price from Nike.com with a medical discount. This in no way affected the honesty of this review. We put at least 35-50 miles on trainers and 10-25 miles on racing flats prior to reviewing them. Currently we have 60 miles (Matt), and (95) miles (David) on our pairs. Our views are based on our extensive history in the footwear industry and years testing and developing footwear. If you are a footwear rep looking for footwear reviews or consultations on development, we are currently looking to partner with companies to assist, discuss and promote footwear models. Partnership will not affect the honesty of our reviews.

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